EyesProtector is a useful application that helps you avoid computer eye strain and fatigue.
One of its advantages is that it does not interfere with other applications; it silently runs in the background and calculates when you need to take a break or do eye gymnastics, depending on the time you spend working on the computer, and sends alerts popping-up messages from its system tray icon.
From its main window, you can monitor the time you spend working. You can perform eye exercises and have a break (lock the user session). Besides, you can find many customizable options, just to mention some of them, you can set the time of allowed solid work, change the time for "tired eyes" messages, change the sound alerts, and set text reminders.
The last thing to mention is that the program comes in different versions. The full version allows you to configure the parameters for different users. The Lite edition has the User Management System disabled, and the free edition allows you to use only the default settings defined by the program. Anyway, whatever version you choose, this program is a good option to help you in preventing eye strain.